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Archived

Avalanche Forecast

Feb 14th, 2018–Feb 15th, 2018
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Olympics.

Identify and avoid steep slopes with wind deposited snow such as near fresh cornices, on snow drifts, or below blowing snow. Small shallow wind slabs have formed along ridges in wind exposed areas. Icy snow surfaces still exist below the new snow. Be careful if traveling on steep firm slopes where it will be difficult to stop a fall.

Detailed Forecast

Small shallow wind slabs will be found on lee slopes near and above treeline. Identify and avoid areas of wind transported snow. Blowing snow, fresh cornices, and snow drifts all indicate that wind slabs are present within the terrain.

In sheltered areas, several inches of new snow will cover the icy old snow surface. Use caution if traveling on steep icy slopes where stopping a fall may be very difficult.

 

Snowpack Discussion

Several inches of new snow fell Wednesday in the Olympics. This new snow is not expected to have bonded well to the old firm snow surfaces. In wind exposed areas near and above treeline, shallow sensitive wind slabs have likely formed.

Below the new storm snow, a strong, relatively uniform, and spring-like snowpack exists. Unstable snow should be limited to the new snow and its bond with the old snow surface. No other significant layers of concern have been reported within the snowpack.

Observations

No recent observations

Avalanche Problems

Wind Slabs

Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

 

Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..

 

Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.

 

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 1